Electric impulse generator



Aug. 26, 1947. s, PRIDHAM I I 2,426,322

ELECT-RIG IMPULSE'GENERATOR Filed June 30, 1943 w awa /4% Patented Aug. 26, 1947 ELECTRIC IMPULSE GENERATOR Edwin S. Pridham, Oakland, Calif., assignor to The Magnavox Company, Fort Wayne, Ind., a corporation of Delaware Application June 30, 1943, Serial No. 492,975

Claims.

This invention relates to electric impulse generators of the magneto type, by means of which impulses of electric energy are produced in operating circuits in response to changes in flux distribution occasioned by mechanical changes in the magnetic circuits.

It is an object of the invention to provide an electric impulse generator of simple construction and utilizing to maximum advantages the electric energy producing powers of the magnetic circuit.

Other and further objects and advantages of the invention will be apparent from the following description when taken in connection with the accompanying drawings, Wherein Figure 1 is a diagrammatic illustration of an impulse generator embodying the invention;

Figure 2 is a view similar to Figure 1, but showing the parts in a difierent position of operation; and

Figure 3 is a diagrammatic illustration of a second form of impulse generator embodying the invention.

As shown in Figures 1 and 2, an impulse generator embodying the invention may comprise a magnetic device such as a permanent magnet 2 having spaced side arms 4 and 6 providing, respectively, a north pole and a south pole, and cooperating with an armature rod or bar 8 appropriately mounted for movement toward and away from the magnet 2. A coil I0 is wound upon the armature 8 and one end of the coil is connected as by wire l2 to a switch blade I4 carrying a switch contact l6, while the other end of the coil is connected, preferably by a flexible or extensible wire or connector l8 to a switch blade 20 carrying a switch contact 22. The switch blades l4 and 20 may be connected by wires 24 and 26 to an electrical load or energy absorbing device 28. An actuating member or operator, diagrammatically indicated at 30, may be connected to the armature or the magnet to cause relative movement thereof. One or the other, or both, of the switch blades l4 and 20 may be formed of a spring plate, strip, or member of any suitable resilient material, causing the switch contacts l6 and 22 to remain in engagement during a predetermined relative movement of the magnet and armature, .so that the switch contacts which short the coil ID will remain in engagement upon the initial relative movement of the armature and magnet and will be brought into engagement just before the armature contacts the magnet. By adjustment of set screw 3l, bearing upon blade 20, the operation of the contacts can be timed in relation to the spring and closing of the magnetic circuit and adjusted to function at a definite air gap.

The armature and magnet being in the position shown in Figure 1 and a sufiicient force being applied to the actuating member 30 to move the armature, the armature starts to open the magnetic circuit but the coil circuit being still shorted, a heavy current flows into the coil, magnetizing the armature in such a direction that it resists the opening of the magnetic circuit. As further force is applied to overcome this additional resistance, the armature moves away from the magnet, the contacts I6 and 22 open, and the energy stored in the magnetic circuit is delivered to the load or energy absorbing device 28. The magnet and armature now occupy the relative positions shown in Figure 2.

When the armature is moved from the position of Figure 2 toward the position of Figure 1, the flux through the armature increases rapidly as the armature approaches the magnet, and just before the armature closes the magnetic circuit, the heavy switch contacts 16 and. 22 come together so that at the time of maximum rate of change of flux, the coil is short circuited. A heavy current flows in the shorted coil, magnetizing the armature in such a direction as to impede the closure of the gap between the armature and the magnet, and to require the application of a greater force through the actuating member than if the coil were open. If the armature is now moved in the opposite direction or away from the magnet before the stored energy is dissipated, a greater resistance fill be offered to the openin of the magnetic circuit, and hence a greater amount of energy will be delivered to the load than if the coil was not shorted before the magnetic circuit was closed.

It will be evident also that the making and breaking of these contacts i6 and 22 effects instantaneous initiation and cut-off of the flow of current to the load or energy absorbing device 23, thus minimising the dissipation of .energy during the time that current or voltage is being built up to the value required to operate the load or to force a current through the energy absorbing device.

Since in this device the energy is used only for short periods of time, the short circuit does not harm the armature but permits utilization .of the device at maximum effioiency in respect to the energy transferred.

In Figure 3 there is disclosed a balanced armature type of magneto of any desired shape and having a north pole 32 and a south pole .34.

The magnet is provided with a plate or bar 36 forming a polar extension for the north pole, and a plate or bar 38 forming a polar extension for the south pole. The polar extension 36 provides spaced north pole pieces or shoes 40 and 42, and the polar extension 38 provides south pole pieces or shoes 44 and 46.

An armature rod or bar 48 is supported between the polar extension by the magnetic forces acting on the armature when placed between the pole shoes. A coil 50 is mounted on the armature and is connected at one end to switch blades 52 and 54 carried by the armature. The other end of the coil is connected by a flexible lead or connector 56 to a switch blade 58 mounted on, or fixed relative to, the polar extension 36 and by a flexible lead or connector 60 to a switch blade 62 mounted on, or fixed relative to, the polar extension 38.

The switch blades 52, 54, 58, and 62 carry switch contacts 64, 66, '68, and 10, respectively. One or both of each pair of switch blades 52-58 and 54-62 is made of or mounted on a spring plate, strip, or member of any suitable resilient material, and one or both of the blades 5862 provided. with an adjusting set screw H to time the operations of the switches in relation to the opening and closing of the magnetic circuits and so that the switch contacts of each pair will close just prior to the engagement of the armature with the magnet and remain closed during the initiation of movement of the armature.

An electrical load or energy absorbing device 72 is connected by wires 14 and 16 to the switch blades 52 and 58. It is evident, of course, that it is immaterial to which pair of switch blades the load is connected, for in any event current will fiow to the load only when both pairs of switch contacts are open. When the armature is at rest, it lies diagonally of the polar extensions in contact with one north pole and a diagonally opposite south pole, that is to say, the armature will, at rest, be in contact with the north pole 4E] and south pole 46, or the north pole 42 and the south pole 44. When the armature is in a rest position the coil is shorted by either the pair of contacts 64 and 68 or the pair of contacts 66 and H1. The armature is moved or actuated between its alternative positions through an operating member or rod 18 provided with a finger grip 80, or other force transmitting member to which the actuator or operator may be connected. The member or rod 18 is in the nature of a strong spring secured at one end to the armature, and secured at its other end to an operator or actuator so that energy is stored, or a force built up, therein by the actuator until the magnetic resistance to the movement of the armature is overcome and then causes the armature to move rapidly.

Pressure applied to the armature in the proper direction will tend to move it from on or the other of its diagonal positions to eifect a slight movement thereof before the then engaged shorting contacts are open. Just as the armature breaks away from the magnet, a heavy current is created in the coil 56 by the sudden change in the amount of flux threading the armature, and the magnetic force created by this heavy current resists the further movement of the armature so that a greater force must be applied to the armature than if the coil was not shorted. The force applied being sufiicient to overcome this resistance, the short circuit on the coil is opened and the energy stored in the magnetic circuit, as a result of the heavy current in the short circuited coil, produces a surge of energy as it is delivered to the load or energy absorbing device 12, along with the energy created by the further rapid movement of the armature into engagement with the other diagonally opposite pair of poles. Just before the armature engages the other pair of poles, the other pair of switch contacts is closed to short-circuit the coil during the instant that the flux through the armature is changing at the greatest rate, so that energy is stored in the magnetic circuit while the heavy shortcircuit current is flowing through the coil. This energy may then be delivered to the load upon reverse movement of the armature if, before that stored energy is dissipated, the short circuit is removed from the coil.

By means of the adjustable set screw 3| or H, the opening and closing of the short-circuited armature coil is timed in direct relation to the opening and closing of the air gap of the magnetic circuit thus varying to a determined extent the magnetic energy stored in the armature and releasable to the operating circuit When the short circuit is opened.

Changes may be made in the form, construction, and arrangement of the parts without departing from the spirit of the invention or sacrificing an of its attendant advantages, and the right is hereby reserved to make all such changes as fairly fall within the scope of the following claims:

What I claim is:

1. In an electric impulse generator, means providing opposed pairs of magnetic pole faces, an armature movable between said pole faces, a coil inductively coupled to the armature, an operating circuit connected to said coil, switches operatively connected to said armature and connected to said coil to establish a short circuit around said coil as the armature approaches each pair of said pole faces and to break the short circuit upon initiation of movement of the armature from each pair of said pairs of pole faces toward the other pair of pole faces, and means for moving said armature from each pair of pole faces to the other.

2. In an electric impulse generator, a permanent magnet having a movable armature, a coil wound about said armature, a pair of interengageable switch contacts connected across opposite ends of said coil, an operating circuit connected across opposite ends of said coil, one of r said switch contacts being supported by said armature and the other being supported by said magnet, means for moving said armature to and from said magnet, and adjustment means for adjusting said contacts relatively to cause said contacts to close just prior to the engagement of said armature with said magnet and to open just subsequent to the disengagement of the armature from the magnet.

3. In an electric impulse generator, a permanent magnet having spaced pole faces, and an armature movably supported between said pole faces solely by the magnetic action of the field between said pole faces, a coil wound about said armature, a pair of stationary switch contacts, a pair of switch contacts movable with said armature for alternately engaging said stationary contacts, one end of said coil being connected directly to said movable contacts and the other end directly to said stationary contacts, an operating circuit connected across opposite ends of said coil, said armature being so constructed and arranged as to move the contacts out of engagement with the stationary contacts for a substantial portion of the movement of the armature, and actuating means including energy storing means for actuating said armature in both directions.

4. In an electric impulse generator, load circuit terminals, an induction coil connected to said terminals and having a magnetic circuit including members relatively movable to vary the flux threading said coil whereby to induce voltages in said coil, cooperating relatively movable contacts electrically connected to opposite ends of said coil, one of said contacts being mechanically connected to the armature for movement therewith, and adjustment means for adjusting said contacts relatively to cause the contacts to short circuit said coil and said load circuit terminals On initial relative movement of said members and to break said short circuit when the rate of change of the magnetic flux threading the coil is greatest whereby maximum energy is delivered to the load terminals.

5. In an electric impulse generator, means providing opposed pairs of magnetic pole faces, an armature movable between said pairs of pole faces, a coil inductively coupled to the armature, a load circuit electrically connected to opposite ends of said coil, movable contact means mechanicall connected to said armature and electrically connected to one end of said coil and cooperating stationary contacts oppositely positioned with respect to said movable contact means and electrically connected to the other end of said coil, and adjustment means for adjusting said contacts and contact means relatively to cause said contacts and contact means to establish a short circuit around said coil just prior to the time the armature engages each pair of said pole faces and break the said short circuit just after the armature disensages each one of said pair of pole faces in moving toward the other pair of pole faces.

EDWIN S. PRIDHAM.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 5 Number Name Date 1,307,342 Brown June 24, 1919 1,290,190 Herrick Jan, 7, 1919 Certificate of Correction Patent No. 2,426,322. August 26, 1947.

EDWIN S. PRIDHAM It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Column 2, line 34, for fill read will; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Oflice.

Signed and sealed this 2d day of December, A. D. 1947.

THOMAS F. MURPHY,

Assistant Commissioner of Patents.

Certificate of Correction Patent No. 2,426,322. August 26, 1947.

EDWIN S. PRIDHAM It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Column 2, line 34, for fill read will; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 2d day of December, A. D. 1947.

THOMAS F. MURPHY,

Assistant Oommz'ssioner of Patents. 

